Projected land-cover changes and their consequences on the supply of Ecosystem Services in Uruguay

Grasslands are one of the most human-modified biomes in the world due to the expansion of croplands and afforestation. In the scenario of productive intensification, it is necessary to generate alternatives to model land-cover changes and their environmental consequences. The objective of this study was to generate land-cover projections and quantify the future impact of these dynamics on the supply of ecosystem services in Uruguay. For that, land-cover maps, Markov-chains models, and an index of the supply of ecosystem services (ESSI) were utilized. Based on the land-cover maps, transitions probabilities between classes for two time periods (2000–2010 and 2010-2019) were calculated, and two Markovian-chain models were performed. With the projected land-cover maps, spatial models were used to relate the proportion of croplands and grasslands with the ESSI. The results indicate a continuous increase of croplands and afforestation for the next decade. Grasslands will remain the most abundant land-cover, reaching 46% in 2037. The highest probability of persistence was, in both periods, for grasslands, while the probability of persistence increased by 60 and 13% for croplands and afforestation, respectively. The ESSI shows a 5% of decrease between 2000-2037. These findings provide important empirical evidence for territorial planning and sustainable management.Agencia Nacional de Investigación e Innovació

Controls of forage selective defoliation by sheep in arid rangelands

Selective grazing by domestic livestock is a major control of plant community structure anddynamics in drylands. However, grazing impact predictions supporting management decisions are fre-quently based on average biomass consumption, neglecting selectivity. We evaluated the relative impor-tance of grazing pressure, total and each species density, and plant dead biomass proportion as drivers ofselective defoliation by sheep in three dominant native grass species in Patagonian steppes. Species werePoa ligularis,Festuca pallescens,andPappostipa speciosa, whicha prioripresent different preference degree bysheep. The relevance of these drivers for differently preferred species has not been simultaneously studied.We recorded the defoliation frequency and degree of the three species (dependent variables) throughout112field surveys. Besides, we recorded grazing management and vegetation structure descriptors (inde-pendent variables).Poa ligulariswas highly defoliated (90% of plants), and grazing pressure was the lead-ing driver (asymptotic exponential relationship). ForF. pallescens, almost 70% of plants were defoliated,and defoliation non-linearly increased as grazing pressure rose and linearly decreased as both its dead bio-mass proportion andP. ligularisdensity increased. ForP. speciosa, defoliation was low (20% of plants) andlinearly decreased as both its dead biomass proportion and the density of the other two species increased.Grazing pressure played a negligible role in this species. These patterns confirmed thatP. ligularis,F. palles-cens,andP. speciosa,respectively, present high, intermediate, and low preference degree by sheep. In con-clusion, ourfindings suggest that (1) selective defoliation can be satisfactorily predicted as function ofgrazing pressure, species densities, and plant dead biomass proportion; (2) grazing pressure becomes amore relevant driver as species preference rises and its effect on defoliation is markedly non-linear; (3) thedead biomass proportion and the abundance of highly preferred species are the leading factors determin-ing less preferred species defoliation; and (4) grazing pressure management by itself is not enough toreduce the high defoliation of preferred species and increase the defoliation of non-preferred species. Thisknowledge is critical for developing effective management practices to control forage species defoliation inrangelands worldwide where species with different preference by herbivores coexist

The law is spider’s web: an assessment of illegal deforestation in the Argentine Dry Chaco ten years after the enactment of the “Forest Law”

Deforestation control is one of the major challenges worldwide. The aim of this study was to analyse deforestation under the Forest Law in the Argentine Dry Chaco ecoregion a decade after its enactment and to assess compliance with forest protection standards in this region. For this purpose, we overlapped the provincial land zoning maps with an annual plot level deforestation database and, for some provinces, with the rural cadastral cartography. Deforestation exceeding the values allowed by the Forest Law and the provincial zonings during this period totalized 722,782 ha (28% of the total deforested area in this period), of which 59,732 ha were deforested in high conservation value areas, 644,396 ha in medium conservation value areas and 18,654 ha in low conservation value areas. While Santiago del Estero was the province with the highest deforested area in medium conservation value areas, Córdoba was the province with the highest deforested area in high conservation value areas. Our results are an important step towards identifying discrepancies between the legal objectives and the observed results and represent an input to think about solutions to improve the environmental governance of the region

Río de la Plata Grasslands: how did land-cover and ecosystem functioning change in the 21st century?

The Río de la Plata Grasslands region is one of the largest plains in the world, covering a significant portion of the southern Brazilian grasslands. This temperate sub-humid region is also one of the most diverse grassland areas globally. However, in the last decades, important land-use and land-cover changes occurred threatening the natural ecosystem and the provision of essential ecosystem services. In this chapter, we provide an overview of the primary land-use and land-cover changes that have occurred in this region over the last two decades. We also discuss some of the consequences derived from these changes on the ecosystem functioning, the supply of ecosystem services, and the human appropriation of primary production. Finally, we evaluate the observed transition trends among land-use and land-covers and speculate on the most likely changes that may occur in the next few years.Agencia Nacional de Investigación e Innovació

Carbon stocks and potential sequestration of Uruguayan soils: a road map to a comprehensive characterization of temporal and spatial changes to assess carbon footprint

Carbon net emission is a critical aspect of the environmental footprint in agricultural systems. However, the alternatives to describe soil organic carbon (SOC) changes associated with different agricultural management practices/land uses are limited. Here we provide an overview of carbon (C) stocks of non-forested areas of Uruguay to estimate SOC changes for different soil units affected by accumulated effects of crop and livestock production systems in the last decades. For this, we defined levels based on SOC losses relative to the original (reference) SOC stocks: 25% or less, between 25% and 50%, and 50% or more. We characterized the reference SOC stocks using three approaches: (1) an equation to derive the potential SOC capacity based on the clay and fine silt soil content, (2) the DayCent model to estimate the SOC stocks based on climate, soil texture and C inputs from the natural grasslands of the area, (3) an estimate of SOC using a proxy derived from remote sensing data (i.e., the Ecosystem Services Supply Index) that accounts for differences in C inputs. Depending on the used reference SOC, the soil units had different distributions of SOC losses within the zones defined by the thresholds. As expected, the magnitude of SOC changes observed for the different soil units was related to the relative frequency of annual crops, however, the high variability observed along the gradient of land uses suggests a wide space for increasing SOC with agricultural management practices. The assessment of the C stock preserved (CSP) belowground and the potential for increasing C accumulation or sequestration (CAP) are critical components of the C footprint of a given system. Thus, we propose a methodological road map to derive indicators of CSP and CAP at the farm level combining both, biogeochemical simulation models and conceptual models based on remote sensing data. We recognize at least three critical issues that require scientific and political consensus to implement the use of this propose: (1) how to define reference C stocks, (2) how to estimate current C stocks over large areas and in heterogeneous agricultural landscapes, and (3) what is a reasonable/acceptable threshold of C stocks reduction

Performance of real evapotranspiration products and water yield estimations in Uruguay

Real evapotranspiration (ETR) is a key variable in socio-ecological systems since it is related to the food supply, climate regulation, among others. Also, ETR strongly determines the water yield (WY) at the catchment level (water available for consumption or irrigation). In that sense, quantifying ETR and WY fluctuations linked to various human pressures is essential for comprehensive water planning. In the last decades, remote sensing ETR estimations have become increasingly performed worldwide for hydrological monitoring. In Uruguay, there are several attempts to quantify the ETR through different approaches. However, assessments related to the performance of the estimates of different sources/products, particularly from remote sensing, are still lacking. The main objectives of this article were: a) to evaluate the performance of different spatial explicit approaches to estimate real ETR and b) to estimate and analyse the variability in water yield derived from the different ETR sources/products for three climatically contrasting years. To achieve this, we used four remote sensing ETR products (PMLv2, MOD16A2, Jackson et al. 1977 and Di Bella et al. 2000), with different spatial and temporal resolutions (from 500 to 1000-m and 8 to 16-d), and two water balance models at two scales, national (INIA-GRAS) and micro-watershed level (Silveira et al. 2016). Our results suggest that MODIS and PMLv2 remote sensing products demonstrated better performances. Both products have high spatial (500-m) and temporal (8-d) resolution, captured seasonal differences between land-covers and showed positive and high correlations with the annual precipitation and productivity. The differences found between products have direct implications on the WY estimates, not only in the quantity but also in its spatial pattern. Future studies should explore MODIS and PML ETR estimations for understanding hydrological and ecological processes, global climate change research, agricultural drought detection and mitigation, and water resource management.Agencia Nacional de Investigación e Innovació

Sistemas agrícolas y silvopastoriles en el Chaco Semiárido. Impactos sobre la productividad primaria

La productividad primaria neta (PPN) se define como la tasa a la cual se acumula biomasa por unidad de área y de tiempo, y se la considera una variable integradora del funcionamiento de los ecosistemas. El desmonte y los cambios en el uso del suelo que afectan gran parte de la región del Chaco Semiárido pueden impactar sobre las ganancias totales de C y su estacionalidad. Trabajos previos en la región utilizan índices espectrales de vegetación como subrogado de la PPN. Sin embargo, arriban a resultados dispares y sólo se circunscriben a lo que sucede con la parte aérea (PPNA), sin considerar los cambios que ocurren en la porción subterránea (PPNS), que suele variar entre tipos fisonómicos de vegetación. Sobre la base del modelo de eficiencia en el uso de la radiación, de información espectral derivada de sensores remotos y de relaciones PPNS/PPN de la bibliografía, el objetivo de este trabajo fue cuantificar el efecto de la transformación en el uso y la cobertura del suelo sobre la PPN, y su variación estacional. En particular, se evaluó el cambio de la PPN en sistemas agrícolas y silvopastoriles con un componente leñoso variable, respecto del bosque original. En general, se observó que los usos del suelo que presentaban una mayor productividad aérea mostraban, al mismo tiempo, los menores niveles de productividad subterránea. El doble cultivo trigo-maíz presentó la mayor PPN total, significativamente superior a la de los sistemas silvopastoriles entre 5 y 25% de cobertura arbórea, y a los cultivos de trigo-soja y soja de primera. Sin embargo, su productividad no varió significativamente de la del bosque, las pasturas megatérmicas y el maíz de primera. Los resultados obtenidos no sólo aportan información sustancial para concluir cuantitativamente en términos de la magnitud del cambio en unidades de materia seca, sino que también permiten establecer un orden o ranking más apropiado de las coberturas y usos del suelo en cuanto a la productividad total

Onset of deep drainage and salt mobilization following forest clearing and cultivation in the Chaco plains (Argentina)

Semiarid sedimentary plains occupied by dry forest ecosystems often display low groundwater recharge rates and accumulation of salts in the soil profile. The transformation of these natural systems to rain‐fed agriculture has led to raising water tables and a slow, but steady, process of groundwater and soil salinization in vast areas of Australia. In the semiarid plains of Chaco (central South America), unprecedented deforestation rates are taken place. Based on deep soil sampling (0–6 m) in seven paired stands under natural dry forest, rain‐fed agriculture and pasture, with different age of clearance (>30 years, 20 and 3 years) in Salta, Argentina, we provide evidence of groundwater recharge increase and onset of salt mobilization in areas where forests were replaced by annual croplands. Soils with higher water and lower chloride content are evidence of deep percolation and salt leaching. In Salta, stands subject to 30 years of rain‐fed cultivation had profiles with 30–46% higher moisture content and 94% lower chloride stocks compared to dry forest (0.05 ± 0.04 kg/m2 versus 0.77 ± 0.4 kg/m2). Estimates of groundwater recharge based on the displacement of chloride peaks suggested values of 27–87 mm yr−1 for agricultural soybean stands, and 10.4 mm yr−1 for pastures. While hydrological shifts in the regional groundwater system are poorly monitored and understood, our findings show that it is potentially sensitive to land use changes and to salinization processes.EEA SaltaFil: Amdam, M. Laura. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Aragón, Myriam Roxana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Jobbagy Gampel, Esteban Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Volante, Jose Norberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Paruelo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentin

A data-driven methodological routine to identify key indicators for social-ecological system archetype mapping

The spatial mapping of social-ecological system (SES) archetypes constitutes a fundamental tool to operationalize the SES concept in empirical research. Approaches to detect, map, and characterize SES archetypes have evolved over the last decade towards more integrative and comparable perspectives guided by SES conceptual frameworks and reference lists of variables. However, hardly any studies have investigated how to empirically identify the most relevant set of indicators to map the diversity of SESs. In this study, we propose a data-driven methodological routine based on multivariate statistical analysis to identify the most relevant indicators for mapping and characterizing SES archetypes in a particular region. Taking Andalusia (Spain) as a case study, we applied this methodological routine to 86 indicators representing multiple variables and dimensions of the SES. Additionally, we assessed how the empirical relevance of these indicators contributes to previous expert and empirical knowledge on key variables for characterizing SESs. We identified 29 key indicators that allowed us to map 15 SES archetypes encompassing natural, mosaic, agricultural, and urban systems, which uncovered contrasting land sharing and land sparing patterns throughout the territory. We found synergies but also disagreements between empirical and expert knowledge on the relevance of variables: agreement on their widespread relevance (32.7% of the variables, e.g. crop and livestock production, net primary productivity, population density); relevance conditioned by the context or the scale (16.3%, e.g. land protection, educational level); lack of agreement (20.4%, e.g. economic level, land tenure); need of further assessments due to the lack of expert or empirical knowledge (30.6%). Overall, our data-driven approach can contribute to more objective selection of relevant indicators for SES mapping, which may help to produce comparable and generalizable empirical knowledge on key variables for characterizing SESs, as well as to derive more representative descriptions and causal factor configurations in SES archetype analysis